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Revision f9092b10

IDf9092b108f7b35e463e58bd3dd348ff002ba9e63

Added by Markus Armbruster over 10 years ago

savevm: Survive hot-unplug of snapshot device

savevm.c keeps a pointer to the snapshot block device. If you manage
to get that device deleted, the pointer dangles, and the next snapshot
operation will crash & burn. Unplugging a guest device that uses it
does the trick:

$ MALLOC_PERTURB_=234 qemu-system-x86_64 [...]
QEMU 0.12.50 monitor - type 'help' for more information
(qemu) info snapshots
No available block device supports snapshots
(qemu) drive_add auto if=none,file=tmp.qcow2
OK
(qemu) device_add usb-storage,id=foo,drive=none1
(qemu) info snapshots
Snapshot devices: none1
Snapshot list (from none1):
ID TAG VM SIZE DATE VM CLOCK
(qemu) device_del foo
(qemu) info snapshots
Snapshot devices:
Segmentation fault (core dumped)

Move management of that pointer to block.c, and zap it when the device
it points becomes unusable.

Signed-off-by: Markus Armbruster <>
Signed-off-by: Kevin Wolf <>

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